EXPLANATION OF PLATE LIV. 



Page 



FIG. 1. Orthonychia chesterense 191 



la. Lateral view. (Key es collection.) 

 Ib. Lateral view of another specimen . 



Ic. Lateral aspect of specimen attached to Pterotocrinus acutus, with only a 



portion of the dome shown and the radial dome plates broken away. 



Id . View from above of another specimen resting on the same species of cri- 



noid. (Ib-d in collection Wachsmuth and Springer.) 

 Carboniferous, Kaskaskia limestone. 



FIG. 2 . Orthonychia acutirostris 190 



2a. Lateral view 



2b. Dorsal view of another specimen. ( A. fterW bitfield.) 



2c. Lateral aspect of same. 



Carboniferous, Keokuk limestone . 



FIG. 3. Igoceras pabulocrinus '. 184 



3a-b. Specimen attached to Platycrinus hemisphericus Meek & Worthen. (Keyes 



collection . ) 



Sc-k. Other specimens which were also attached to the same species of crinoid. 

 31. Lateral view of same. 

 8in . Posterior view of a natural cast showing muscular scars . (After Meek & 



Worthen ) 



Carboniferous, Keokuk limestone. 



FIG. 4. Capulus spinigerus 



4a. Lateral view. (After' Worthen.) 

 4b. Another aspect of same. 



FIG 5 . Capulus parvus 180 



5a . Dorsal view of specimen supposed to be the type . 



(Museum State University of Missouri.) 

 5b. Lateral aspect of same. 

 5c. Posterior aspect of same. 

 5d . Posterior view of another specimen . (After White . ) 



FIG. 6. Naticopsis tortum (Meek) . 



6a-b. Apertural and dorsal views of type. (Collection of J. S. Newberry.) 



FIG. 7. Portion of the vault of Strotocrinus rcgalis Hall, showing the impreesion 

 made by a growing shell pf Capulus. 



FIG. 8. Calyx of Platycrinus pileiformis Hall, showing the impression made by a 

 Capulus on the anal side of the crinoid. 



